The paper first overviews the CIE system of colorimetry, covering CIE 1931 color matching functions, XYZ tristimulus values, x, y diagram, 1976 u', v' diagram, and evolvement of CIELUV and CIELAB color spaces and color difference formulae. The paper then reviews the measurement of object colors introducing CIE standard illuminants and the CIE terminology for color and reflectance measurements, then the measurement of lightsource colors (including displays) with calculation of correlated color temperature and color rendering indices. The paper also discusses practical aspects of color measurements for imaging applications using spectroreflectometers, spectroradiometers, and tristimulus colorimeters. Overview is given for calibration and verification of instruments' accuracy, spectral irradiance and reflec-tance standards (available from national laboratories), and uncertainty components.